I. Field of the Invention
This invention pertains to physical security systems such as perimeter intrusion detection systems, and particularly to an intelligent processor unit suitable for use with conventional sensors in a physical security system, and a method for operating such a processor unit.
II. Prior Art and other Considerations
In general, physical security systems include sensors which monitor an associated area or zone. When a sensor detects activity within its zone, the sensor changes its output state, which in turn can result in activation of an alarm. Such sensors are utilized to detect intrusions that compromise security of the monitored premises, such as a military installation or an industrial facility. Some of the activity detected by security sensors does not necessarily compromise the security of monitored premises, such as background noise, noisy weather conditions, or perimeter-penetrating roamings of animals, for example. An event which does not compromise security, but which nevertheless is detectable by sensors, is generally referred to as a "nuisance".
When alarms are frequently activated by nuisances, one of two scenarios often develop. In some situations, human security guards monitoring the alarms become dulled and inattentive, with the result that security becomes lax. In other situations, each nuisance alarm condition is investigated, requiring inordinate effort.
Sometimes sensors do not properly detect an intrusion, resulting in a "missed detection". Such can occur, for example, when equipment at a physical security system is misadjusted in hopes of reducing the number of nuisance alarms.
Physical security systems are typically evaluated by plotting the probability of detection of the system against its probability of nuisance alarm. The resulting curve, known as the receiver operating curve or "ROC" curve, reflects the efficiency of the security system. An efficient physical security system has a high probably of detection and a low probability of nuisance alarm.
Applicants have previously proposed an efficient intrusion detection system for monitoring a plurality of monitored areas or phenomenology zones. The previously proposed system comprised a local area network (LAN) which linked together three types of nodes: a basic signal processing node; an enhanced node; and, a display and control node. The basic node monitored a set of sensors, performed signal conditioning and certain signal processing, and sent partially processed data to an enhanced node via the LAN. In one configuration of the proposed system, a basic node was provided at each sensor zone, there being a plurality of sensors in the overall system. Each enhanced node served several basic nodes by performing more detailed signal processing and making classification decisions (e.g., whether an alarm should be activated with respect to a certain zone). When an alarm was determined to have occurred, the enhanced node sent information to the display and control node which displayed the alarm and prompted security personnel for further actions.
When an event, such as an intrusion or a nuisance, occurred in the system previously proposed by Applicants, the basic node detecting the event applied data to the LAN at quarter second intervals. The enhanced nodes included a plurality of classifier networks, including a permanently programmed "switch" classifier and one or more retrainable branch classifiers. The switch classifiers were utilized to determine the existence of abnormal conditions, such as bad weather or heavy background noise, and to direct processing to a branch classifier suitably pre-programmed for making classifications under the abnormal condition. The classifiers used data-extracted "features" occurring over the last second of time as input to their polynomials for obtaining a classifier output value. The classifier output value was compared to a threshold value to determine if an event was an intruder or a nuisance.
The classifiers included in Applicants' previous system were reprogrammable or retrainable to reflect newly learned truth. In this respect, data associated with an event was archived at the control node. If an event were incorrectly classified as an intrusion rather than a nuisance, "ground truth" for properly classifying the event could later be input to the archiving area of the control node. Subsequently, the archived data was transferred to a separate workstation which developed new classifiers for the enhanced node. These new classifiers were then downloaded to the enhanced node via the LAN.
Most existing security conscious facilities have, at considerable costs, already installed basic security systems. Conventional security systems typically include one or more sensors associated with each of a plurality zones. Examples of such sensors include fence monitors (such as taut wire devices); magnetic seismic sensors (i.e., "MILES"); geophones, microwaves sensors ("RACON"); and ported coax cables ("SENTRAX"). These sensors generally have a relay closure which changes state (e.g., opens) when the sensor detects an event. When a transponder associated with a sensor detects a change of state of the relay closure, the transponder sends a signal to a central monitoring station.
Facilities having conventional security systems comprising sensor relay closures and transponders are generally inefficient. The environment surrounding these conventional sensors cannot be controlled, and the sensors cannot adapt for changing environment or background conditions. But with considerable capital investment in their existing conventional security systems, these facilities are not prone to dismantle their existing systems for replacement by more advanced systems, including the LAN-based intelligent system previously proposed by Applicants. Nevertheless, such facilities would greatly benefit from enhanced intrusion/nuisance discrimination.
Therefore, it is an object of this invention to provide apparatus for intelligently enhancing conventional physical security systems and method for operating the same.
An advantage of the present invention is the provision of a modular unit for intelligently enhancing conventional physical security systems.
Another advantage of the present invention is the provision of a retrainable unit for intelligently enhancing conventional physical security systems and method for operating the same.
Yet another advantage of the present invention is the provision of a remotely configurable unit for intelligently enhancing conventional physical security systems and method for operating the same.
Still another advantage of the present invention is the provision of a unit for intelligently enhancing conventional physical security systems which can function independently of other aspects of the physical security system.
Another advantage of the present invention is the provision of a unit for intelligently enhancing conventional physical security systems which is capable of archiving data descriptive of events occurring in a zone associated with the unit.